When imaging a specific structure in a subject, it is needed in some cases to analyze dynamic motions of the specific structure, in other words, it is needed in some cases to track the specific structure within a period of time. This processing can be realized by, for example, acquiring a series of chronological images aiming at the region where the specific structure exists and recognizing the form of the specific structure in each of the images. When recognizing the specific structure, it is possible to adopt for example a manner of manually marking or automatically marking.
However, on one hand, it is impractical to manually mark the specific structure when there are a great number of images; on the other hand, it is difficult to accurately recognize the position of the specific structure in each image automatically because the various limitations to imaging conditions and the inherent characteristics of the specific structure may lead to the low resolution of the images obtained and the unnoticeable characteristics of the specific structure. Therefore, an apparatus and a method are desired that enable automatically tracking a specific structure in a medical image rapidly and accurately.